Stellar compass and great-circle-course projector.



No. 703,|39. Patented lun 24. I902.

R.}T. LAWLESS.

STELLAR COMPASS AND GREAT CIRCLE COURSE PROJECTOR. (Application filed Feb. 24, 1:502. (No Model 2 Sheets-Sheet I.

No. 703,139. Patented June 24,1902. R. T. LAWLESS. STELLAR COMPASS AND GREAT CIRCLE COURSE PROJECTOR.

- (Application tiled Feb. 24, 1902.

2 Sheets-Sheet 2.

(No Mudel.)

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UNTED STATES PATENT OFFICE.

ROBERT T. LAWLESS, OFALAMEDA, CALIFORNIA.

STELLAR COMPASS AND GREAT-ClRCLE-COURSE PROJECTOR.

SPECIFICATION forming part of Letters Patent No. 703,139, dated June 24, 1902.

Application filed February 24, 1902 Serial No. 95,463. (No model.)

To ctZZ whom it may concern:

Be it known that I, RoBERr T. LAwLEss, a citizen of the United States, residing at Alameda, in the county of Alameda and State of California, have invented a new and useful machine, which I have designated the Stellar Compass and Great-Circle-Course Projector, of which the following is a specification.

My invention relates to navigation, andis designed to enable the mariner to steer a true course at any time of the day or night without a compass and also to lay a direct greatcircle-course between any two points.

The construction of the machine is illustrated in the accompanying drawings, in which- Figure 1 represents my invention in perspective with its various dials and parts so set for an observation as to exhibit them in detail. Fig. 2 is a top plan of the same with the base partly broken, showing all its parts at a point of rest. Fig. 3 is a side elevation of Fig. 2, partly in section, as through the line co m on Fig. 2. Fig. at is a front elevation of the same, partly broken, showing the timecircle and its divisions.

The circular stand A,with its three legs B B B and semicircular support 0, all resting on a circular flat wooden base 0, constitutes the framework of the machine. Within this circular stand A and resting in its plane are two circles of brass or other suitable metal, the outer one of which,D,moves on pivots cl d, set in stand A at points correspondingwith the poles or north and south points as desig nated and marked on the inner circle G. This outer circle D is graduated and marked in degrees, beginning at the pivot d, designated as North, and rising in the direction of the point designated as East and ending with 360 at north. This same circle D has also a second graduation or marking indicated onits inner margin, beginning with 0 at the east and west ends of the equatorial axis and rising in both directions to 90 at the poles. It has also a blank space on its outer margin upon which may be designated the names and locations of such stars as may be desired. Attached to the pivot d at the south pole is a cog E, operated by a worm F, by means of which the circle D is moved with nicety and secured in any posiof the compass. volves upon an axis at right angles with the angles to its axis.

and rising in the direction of east terminates at north again with 360, and the other set begins With 0 at both north and south and rises in both directions to 90 at the equator. It has indicated upon it also the usual points This circle G moves or rea'Xis of the circle D. This is accomplished by means of a rod 11, connecting its east and west points, which has bearings h it upon two arms J J, branching from a'single upright support K in the center of the machine, resting in turn upon the semicircular support 0. The circle G is moved and secured in any position by means of a spiral screw L, set in the support K in such manner as to move in the cogged edge of a semicircular frame 9, affixed to the bottom of the circle G at right The rod Z, passing through the leg B and there ending in a milled head,

furnishes the means by which the screw L is This is secured in any desired position by a i set-screw n.

Upon the rod M and beneath the framework of the quadrant N is a pointer .P, which revolves on rod M and is secured in any desired position by a set-screw p.

The pivot dis made to extend alittle beyond the framework of themachine, so as to sustain What I designate as the time-circle Q. This circle is graduated and marked on its outer edge as a sidereal clock and upon an inner line with degrees. It is secured in any desired position by means of a clamp R upon the leg B, which is tightened against it by means of a thumb-screw 7'.

Behind the time-circle Q and between it and the stand A is an upright extension of the leg B, (indicated by 8,) the end of which is turned over in a sharp point 3 upon the face of time-circle Q, to serve as a fixed indicator.

Upon the pivot d and outside the time-circle Q is a hand or pointer T, which may revolve independently on pivot d or may by means of a set-screw t be secured in any position, so that it can only revolve in accord with the circle D.

Similar letters refer to similar parts throu ghout the several views.

The objects attained by this invention and for which the machine is designed are, first, the ascertainment of a true course at any time of the day or night without the aid of a magnetic compass second the ascertainment of a direct course on a great circle of the earth between any two points on the earths surface.

The machine can be used also to work problems of latitude and longitude and the solution of spherical triangles and to ascertain local apparent time and the right ascension of heavenly bodies; but its most valuable uses and those for which it is especially designed are the two hereinbefore specified.

To lay any desired true course with this machine, proceed as follows: First, make the pointer P indicate on the compass G the course which it is desired to lay and steersay, for instance, west. Then set the observers horizontal plane (circle G) at your latitude, which let us assume for purposes of illustration to be 38 north, the latitude of Point Reyes on the Pacific coast. This is done by turning the circle G upon its axis to a position where its north pointis depressed thirty-eight degrees below the level of the outer circle D. This measurement of thirtyeight degrees is made by the quadrant N, which for the purpose is set upon the compass Gin an exact northerly direction. Then ascertain by means of an ordinary mariners quadrant the altitude of the star or other heavenly body which isbeing used for the purpose of the problem. The declination of this star is ascertained by reference to the nautical almanac, or it may be one of the stars "which the observer has already by reference to the nautical almanac, indicated upon the circle D in its true position. Assume, for illustration, that the observer is using the star .Vega, whose declination is thirty-eight degrees forty-one and one-halfminutes north and that its ascertained altitude at the time of the observation is-twenty degrees. Now swing the quadrant N in the direction of the figures on the latitude and declination circle D, indicating the location of the Vega, and at the same time raise the latitude and declination circle D so that thefigures 38 41% indicating the stars declination, will coincide with the altitude 20 upon the quadrant N. Secure the quadrant in that position and its lower point will then indicate upon the compass G the true bearing of the star Vega from the observer. The difference in degrees between this point and the direction indicated by the pointer P will show the difference which must be found to exist between the tars bearing and the ships course in order that the ship may be steering the desired true west course.

In high northern and southern altitudes when circumpolar stars are too near the upper or lower transit there will not be sufficient change in the altitude to make the foregoing process reliable as ascertaining the true bearing of the star. In such cases the timecircle Q should be used in the following man'- ner: First, set the observers horizontal. plane G for your latitude as before. Then,the timecircle Q being set with the mark indicating then turn the latitude and declination circle true course desired, will be found the angle.

which the course of the ship must make with the stars bearing in order to follow the desired course. In using the time-circlein this manner it may be necessary for convenience to make the hand or pointer T parallel with the latitude and declination circle, pointing in the direction of the markindicating eighteen hours, or two hundred and seventy de- IIO grees; but the result in either case will be the same.

To shape a great-circle course by the use of this machine, set the observers horizontal plane G for your latitudethat is, the latitude of the point of departure. Then set the latitude or declination circle D so that it indicates the difference, east or west, as the case may be, between the longitude of the point of departure and the longitude of the point of destination-that is to say, if the difference in longitude is forty degrees then the circle D should be turned so that it shall be upon the proper side that many degrees above the level, measured upon the quadrant N, set in a line at right angles to the axis of D. Now turn the quadrant N around until it cuts upon the latitude and declination circle D the latitude of the point of destination, and it will indicate upon the compass the direct great-circle course desired.

That I claim as my invention, and desire to secure by Letters Patent, is-

1. In the machine of the character described, the combination of a suitable support, a latitude and declination circle mounted to swing in said support, a horizontal plane and compass circle mounted to swing in said support at an angle to the plane of movement of the latitude and declination circle, and means to determine the angular disposition of said two circles with respect to each other.

2. In a machine of the character described, the combination of asuitable support, a latitude and declination circle mounted to swing in said support, a horizontal plane and compass circle mounted to swing in said support and in a plane at substantially right angles to the plane of movement of the latitude and declination circle, and a circular arc to determine the angular disposition of the said two circles with respect to each other.

8. In a machine of the character described, the combination of a suitable support, a latitude and declination circle, a horizontal plane and compass circle, pivotal supports for said circles disposed substantially at right angles to each other, and a quadrant or circular are mounted on the supports of one of said circles to determine the angular disposition of said circles with respect to each other.

4. In a machine of the character described, the combination of a suitable support, a latitude and declination circle, a horizontal plane and compass circle, pivotal supports for said circles disposed substantially at right angles to each other, means for moving said circles upon their pivotal supports, and a quadrant or circular arc mounted on the supports of one of said circles to determine the angular disposition of said circles with respect to each other.

5. In a machine of the character described, the combination of a suitable support, a latitude and declination circle, a horizontal plane and compass circle, each of said circles being provided with suitable graduations, pivoted supports for said circles disposed substantially at right angles to each other and a quadrant or circular arc to determine the angular disposition of any portions of the said circles with respect to each other.

6. In a machine of the character described, the combination of a suitable support, a latitude and declination circle, a horizontal plane and compass circle, pivotal supports for said circles disposed substantially at right angles to each other, and a quadrant mounted to swing upon the support of one of said circles.

7. In a machine of the character described, the combination of a suitable support, a latitude and declination circle, a horizontal plane and compass circle, pivotal supports for said circles disposed substantially at right angles to each other, and a pointer and a quadrant mounted to swing upon the support of one of said circles.

8. In a machine of the character described, the combination of a suitable support, a latitude and declination circle, ahorizon tal plane and compass circle, each of said circles being provided with suitable graduations or scales, pivotal supports for each of said circles arranged at right angles to each other whereby the circles may be swung in planes at right angles, a rod centrally disposed with relation to said circles and movable with one of them, and a quadrant having suitable graduations and mounted to swing on said rod.

9. In a machine of the character described, the combination of a suitable support, alatitude and declination circle, a horizontal plane and compass circle, pivotal supports for said circles arranged substantially at right angles to each other, a time-circle mounted on the supports of one of the first-named circles, and a quadrant mounted upon the support of the other of said circles.

10. In a machine of the character described, the combination of a suitable support, a latitude and declination circle, a horizontal plane and compass circle, pivotal supports for said circles,arranged substantially at right angles to each other, a time-circle and pointer mounted on the supports of one of the first-named circles, and a quadrant mounted upon the support of the other of said circles, and means to clamp the pointer to its support.

11. In a machine of the character described, the combination of a suitable support, a latitude and declination circle, a horizontal plane and compass circle, pivotal supports for said circles arranged substantially at right angles to each other, a time-circle and pointer mounted upon the pivotal support of the latitude and declination circle, means to clamp said pointer and time-circle in desired position, a quadrant mounted to swing upon the support of the horizontal plane and compass circle, all of said circles being provided with suitable graduations.

ROBERT l. LAWLESS.

Witnesses:

SAMUEL M. CRIM, NEAL A. MCCONAGHY. 

